Symptom
Rough running only when cold
The engine runs badly on the first start of the day and clears once warm. A short and specific suspect list — best caught with a scan tool recording from a genuinely cold start rather than diagnosed in a warm workshop.
Also described as: rough when cold, bad when cold, only when cold, cold start problem, runs rough until warm, morning sickness, فقط در حالت سرد بد کار میکند, صبح ها بد کار میکند, motor irregular en frio, funciona mal en frio, va mal en frio, المحرك يخربط على البارد, أداء سيء على البارد, يرتجف على البارد
Some causes mean you should stop driving
1 of the 89 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.
What this usually means
A fault that clears as the engine warms is telling you something specific: the condition causing it is temperature-dependent, and it will not be present in a warm workshop. That single fact is why this complaint is so often returned as no fault found, and why the instruction that matters most is to record from a genuinely cold start rather than to diagnose on arrival.
Russian workshop references set out the mechanisms unusually clearly, and they divide into three kinds. Something that cleans itself up with heat: a spark plug fouled with deposits will foul-out on a cold engine and burn clean once hot, so the cylinder comes back. Something that dries out: damp in the ignition secondary — leads, coil boots, the distributor cap on older engines — lets the spark track to earth instead of jumping the gap, and the leak stops when the moisture evaporates. And something that has not filled with oil yet: a hydraulic lifter that has drained overnight does not take up its clearance until oil pressure reaches it, so the valve does not seat properly for the first minute and the cylinder is genuinely down.
The fourth mechanism has no self-cure and is the one to catch: the mixture is simply wrong for a cold engine. A coolant temperature sensor reading warmer than reality means too little enrichment, and the engine stumbles until the real temperature catches up with what the sensor was claiming — at which point everything appears fine. It produces no warm symptom at all, which is exactly why it goes undiagnosed for months.
On a diesel the population is different: glow plugs, and injectors whose delivery is out of tolerance when cold. Both are measurable rather than inferable, and one bad plug in four is routinely tolerated until a hard frost.
Working through it
| What you find | Likely cause | How to confirm it | What fixes it |
|---|---|---|---|
| Misfire on one cylinder for the first minute, then perfect | A plug fouled with deposits that burns clean once hot, or a lifter that has not pumped up with oil | Record misfire counters from a genuinely cold start. Inspect the plug on that cylinder — deposits will be visible — and listen for lifter noise in the first seconds. | Renew the plugs as a set and address why that cylinder fouls. A noisy lifter that quietens with pressure is a separate repair. |
| Worse in damp weather, better in a dry spell | Ignition secondary leaking to earth through damp — leads, coil boots or a cracked cap | Inspect the leads and boots for tracking marks, and look for a visible corona in the dark with the engine running. Insulation resistance testing confirms it. | Renew the leads, boots or cap. Tracking marks do not clean off. |
| Rough cold with no misfire on any single cylinder | The mixture is wrong for the temperature — a coolant temperature sensor reading warmer than the engine actually is | Compare live coolant temperature against ambient on a car that has stood overnight; they should agree. A sensor claiming 40 °C on a frosty morning is the fault. | Renew the sensor and inspect its connector. This one produces no warm symptom at all, which is why it survives so long. |
| Diesel, rough for the first minute, white-ish smoke | Glow plug circuit, or injector delivery out of tolerance when cold | Measure each glow plug's resistance and confirm the relay energises. Read injector correction values from a cold start — the outlier names the cylinder. | Renew glow plugs as a set with the relay; address the injector separately on its measured correction. |
| Rough cold with lean trims that normalise when warm | Unmetered air — its effect is largest when airflow is lowest, which is a cold fast idle | Smoke-test the induction. Compare trims cold against warm rather than reading them once. | Repair the leaking hose or gasket. Rubber that has hardened leaks worst when cold, which is why the symptom follows temperature. |
| Rough cold on a high-mileage engine, with a rattle for the first seconds | Timing chain slack taken up slowly by oil pressure, so valve timing is briefly wrong | Note whether the rattle and the roughness end together. Read live cam-to-crank correlation on a cold start. | Renew the chain and tensioner. Check the oil grade and change interval — the tensioner depends on prompt pressure. |
-
Misfire on one cylinder for the first minute, then perfect
- Likely cause
- A plug fouled with deposits that burns clean once hot, or a lifter that has not pumped up with oil
- How to confirm it
- Record misfire counters from a genuinely cold start. Inspect the plug on that cylinder — deposits will be visible — and listen for lifter noise in the first seconds.
- What fixes it
- Renew the plugs as a set and address why that cylinder fouls. A noisy lifter that quietens with pressure is a separate repair.
-
Worse in damp weather, better in a dry spell
- Likely cause
- Ignition secondary leaking to earth through damp — leads, coil boots or a cracked cap
- How to confirm it
- Inspect the leads and boots for tracking marks, and look for a visible corona in the dark with the engine running. Insulation resistance testing confirms it.
- What fixes it
- Renew the leads, boots or cap. Tracking marks do not clean off.
-
Rough cold with no misfire on any single cylinder
- Likely cause
- The mixture is wrong for the temperature — a coolant temperature sensor reading warmer than the engine actually is
- How to confirm it
- Compare live coolant temperature against ambient on a car that has stood overnight; they should agree. A sensor claiming 40 °C on a frosty morning is the fault.
- What fixes it
- Renew the sensor and inspect its connector. This one produces no warm symptom at all, which is why it survives so long.
-
Diesel, rough for the first minute, white-ish smoke
- Likely cause
- Glow plug circuit, or injector delivery out of tolerance when cold
- How to confirm it
- Measure each glow plug's resistance and confirm the relay energises. Read injector correction values from a cold start — the outlier names the cylinder.
- What fixes it
- Renew glow plugs as a set with the relay; address the injector separately on its measured correction.
-
Rough cold with lean trims that normalise when warm
- Likely cause
- Unmetered air — its effect is largest when airflow is lowest, which is a cold fast idle
- How to confirm it
- Smoke-test the induction. Compare trims cold against warm rather than reading them once.
- What fixes it
- Repair the leaking hose or gasket. Rubber that has hardened leaks worst when cold, which is why the symptom follows temperature.
-
Rough cold on a high-mileage engine, with a rattle for the first seconds
- Likely cause
- Timing chain slack taken up slowly by oil pressure, so valve timing is briefly wrong
- How to confirm it
- Note whether the rattle and the roughness end together. Read live cam-to-crank correlation on a cold start.
- What fixes it
- Renew the chain and tensioner. Check the oil grade and change interval — the tensioner depends on prompt pressure.
Codes that produce this symptom (89)
Listed with the codes that most typically present this way first — the likeliest place to start.
- P0065 Air Assisted Injector Control Range/Performance Typical of this code Moderate
- P0066 Air Assisted Injector Control Circuit or Circuit Low Typical of this code Moderate
- P0067 Air Assisted Injector Control Circuit High Typical of this code Moderate
- P01CF Cylinder 3 Injection Timing Performance - Over Retarded Typical of this code Moderate
- P0213 Cold Start Injector 1 Typical of this code Moderate
- P0214 Cold Start Injector 2 Typical of this code Moderate
- P0316 Engine Misfire Detected on Startup (First 1000 Revolutions) Typical of this code Moderate
- P0380 Glow Plug/Heater Circuit A Typical of this code Moderate
- P0382 Glow Plug/Heater Circuit B Typical of this code Moderate
- P0383 Glow Plug Control Module 1 Control Circuit Low Typical of this code Moderate
- P0384 Glow Plug Control Module 1 Control Circuit High Typical of this code Moderate
- P050A Cold Start Idle Control System Performance Typical of this code Moderate
- P050B Cold Start Ignition Timing Performance Typical of this code Moderate
- P050D Cold Start Rough Idle Typical of this code Moderate
- P05CC Cold Start A Camshaft Position Timing Performance Bank 1 Typical of this code Moderate
- P064C Glow Plug Control Module 1 Typical of this code Moderate
- P066A Cylinder 1 Glow Plug Control Circuit Low Typical of this code Moderate
- P066C Cylinder 2 Glow Plug Control Circuit Low Typical of this code Moderate
- P066E Cylinder 3 Glow Plug Control Circuit Low Typical of this code Moderate
- P0670 Glow Plug Control Module 1 Control Circuit/Open Typical of this code Moderate
- P067A Cylinder 4 Glow Plug Control Circuit Low Typical of this code Moderate
- P06B9 Cylinder 1 Glow Plug Circuit Range/Performance Typical of this code Moderate
- P06BA Cylinder 2 Glow Plug Circuit Range/Performance Typical of this code Moderate
- P06BB Cylinder 3 Glow Plug Circuit Range/Performance Typical of this code Moderate
- P06BC Cylinder 4 Glow Plug Circuit Range/Performance Typical of this code Moderate
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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